Here's mine on 4G with cake and cake-autorate:
My 4G connection gives a stable 35-40ms unloaded RTT, a variable download bandwidth between 10-80Mbit/s and a variable upload bandwidth between 25-35Mbit/s.
cake-autorate (the most recent release is version 3.1.1) works pretty well in terms of tracking the available bandwidth, albeit as @Pico helpfully points out, if the unloaded latency is not stable, cake with or without cake-autorate cannot improve matters.
Feel free to give cake-autorate a try and post on the OpenWrt cake-autorate thread with your findings and any data or plots, and we can help you configure it for your connection. Since our connections seem rather similar, I suspect the defaults will work pretty well for you.
By the way, if you don't already have an outdoor antenna I'd get one, especially if you have line of sight to your nearest cell tower. You might consider something like the Zyxel NR7101 (which can run OpenWrt). At the very least I think you should spend some time moving around your indoor router to maximise as much as possible the reported LTE stats. Back when I used a Huawei B818-263 indoor 4G router, I was able to drastically improve the LTE stats and connection quality by adjusting the location and orientation of the device - it turned out that it worked best when placed on its side, underneath a window, parallel to the wall and in a particular upstairs room. Tin foil wrapped around the back of the device (in direction opposite to the cell tower) also helped, but it was at that point that I decided to invest in the NR7101 outdoor router, with antenna facing our nearest cell tower.